“We've had a very, very divided country for many years,” Trump said at an event promoting apprenticeship programs. “And I have a feeling that Steve has made a great sacrifice, but there could be some unity being brought to our country.”

The gunman, identified as 66-year-old James T. Hodgkinson of Belleville, Ill., died from injuries suffered in the ensuing shootout with police. Hodgkinson had volunteered for Sen. Bernie Sanders during the 2016 presidential primaries, and his Facebook page was filled with anti-Trump and anti-GOP comments, cartoons, and memes.

Before he opened fire, Hodgkinson reportedly asked if the group practicing was the Republican or Democratic team. Although law enforcement has not officially identified a motive, his apparently strong progressive views are already spurring some reflection on the tone of political discourse surrounding the election and its outcome.

“We’ve got to ratchet down the rhetoric because now’s the time to come together…. We can’t have people who disagree on policy move to the violence I unfortunately witnessed today,” Rep. Rodney Davis, R-Ill., who was at bat when the shooting started, told Sinclair on Wednesday afternoon.

“The idea that you’re going to attack somebody based on the fact that you disagree with them has got to be the definition of senseless…. We need to dial back the rhetoric on both sides,” said Sen. John Boozman, R-Ark.

Some Republicans have made more partisan statements. Rep. Chris Collins, R-N.Y., told a New York radio station Democrats must tone down their “outrageous” finger-pointing and anger toward the president.

Former House Speaker Newt Gingrich attempted to link the attack to Kathy Griffin’s controversial Trump decapitation photos and a performance of “Julius Caesar” that depicts the assassination of a Trump-like leader. He claimed they represent a “pattern” of hostility on the left.

After learning of Hodgkinson’s support for him, Sanders stepped up on the Senate floor Wednesday to make clear that the “revolution” he has been calling for is not a violent one.

“Violence of any kind is unacceptable in our society and I condemn this action in the strongest possible terms,” he said. “Real change can only come about through nonviolent action, and anything else runs against our most deeply held American values.”

Other prominent Democrats tempered their calls for unity with criticism of the right.

“In general, what we need is a desire to solve problems and work together and right now we have the opposite of that,” Sen. Jeff Merkley, D-Ore., said, pointing to the Republicans’ secretive process for crafting their health care reform bill.

Whether responsibility can fairly be placed on one party or politician or not, some say the onus is on President Trump to lead the country away from the extremes of polarization.

“I don’t blame this incident on any political figure…but I do think the president could set a more embracing, softer tone to try to bring people together,” said Sen. Sherrod Brown, D-Ohio.

Since Trump announced his campaign two years ago, his words and positions have generated unusually fierce opposition and atypically passionate support. His rallies were met with protests in many cities, sometimes violent ones, and he repeatedly encouraged his supporters to hit protesters.

Trump’s inauguration in January was followed by one of the largest protests in D.C. history, and the resistance movement has organized many demonstrations across the country since then. Tensions have only grown as questions about the Trump campaign’s relationship with Russia persist.

Conservatives and liberals have cataloged numerous acts of violence by supporters of the other side, and both frequently allege that the other’s incendiary rhetoric will lead to bloodshed.

According to Jeff Coleman, a former member of the Pennsylvania House of Representatives, the rules and norms of political discourse have been eroding for a while, and this shooting is the latest manifestation of that.

“I’d love to say it is a turning point but we’ve had so many examples, not just in the United States but around the world,” said Coleman, author of “With All Due Respect: Recovering the Manners & Civility of Political Combat.”

He has already been disappointed by some of the finger-pointing in the wake of Wednesday’s shooting. He worries that the result could be a crackdown on meaningful expressions of dissent and debate.

“It is one in a series of events that highlights the need for us to rethink whether there is a public square left,” he said. “The basis of civility isn’t disarmament and it is not a hollow, shallow kind of discourse.”

While the evidence so far indicates this shooting is an expression of the current climate of political polarization, Temple University professor Jason Del Gandio was hesitant to ascribe any direct responsibility to the progressive movement or Sanders.

“This was the actions of one lone individual who happened to have progressive politics… You really can’t stop someone from identifying with participating in a movement,” said Del Gandio, author of “Rhetoric for Radicals: A Handbook for Twenty-First Century Activists.”

Some of the loudest, most respected voices in the movement have already denounced the attack, including Sanders and 2016 Democratic presidential nominee Hillary Clinton, who tweeted, “2 sides take the field tomorrow, but we're all ultimately on one team.”

Del Gandio listed a number of reasons why the current political environment seems more heated than the past.

“I would point to certain kinds of social and political conditions that people are living through right now,” he said, including income inequality, climate change, stagnating conditions for the black community, and the erosion of the traditional power and identity of the white middle class.

Others also see an amplifying effect from social media, which increasingly silos users away from conflicting perspectives.

“Social media is like an amazing echo chamber that reaffirms for most people that they’re right and it prevents them from having to realize that there are other arguments,” said Stephanie Martin, a professor of corporate communication and public affairs at Southern Methodist University.

However, she recalled the intense fury from the right against President Barack Obama in 2009 and said it is too soon to tell whether the anti-Trump resistance will be angrier than the tea party movement.

“We tend to live our lives in the superlative,” she said. People often perceive their current moment as the worst or best ever.

Two dynamics are heightening conflicts, though. Neither the dissent on the left nor the energy of Trump’s base on the right has died down much in the months since the election.

“People are really dug in to what they think,” Martin said.

Many previous tragic events have been perceived as tipping points in national debates in their immediate aftermath, but they rarely turn out to be. Calls for a tamping down of rhetoric after the shooting of Rep. Gabrielle Giffords in 2011 were quickly forgotten. Mass shootings at schools and movie theaters have failed to inspire serious legislative action in Congress.

Experts are skeptical that Wednesday’s attack will prove any different.

“These events are becoming so commonplace that we typically experience a moment of unity…but within a few days everything snaps back,” Martin said.

That is already apparent in Trump’s angry tweets Thursday morning, reviving his attacks on the special counsel investigation of Russian interference in the election.

"You are witnessing the single greatest WITCH HUNT in American political history - led by some very bad and conflicted people! #MAGA," he wrote, apparently impugning the integrity of the investigators.

At a press gaggle Thursday, Deputy Press Secretary Sarah Huckabee Sanders refused to address the tweets or the jarring tonal shift from the president’s comments the day before. She referred all questions to Trump’s outside counsel.

The statements Wednesday from political leaders like Sanders and Trump calling for unity are a first step toward improving the tone of discourse, but it is not an easy challenge to solve.

“Nobody agrees on the premise of the problem,” Coleman said.

This is why he considers dialogue and engagement to be vital steps in healing. Fittingly, the congressional baseball game has long been a powerful example of that bipartisan interaction.

“It really does begin with an individual saying I’m going to diversify, at least understand how another side is arriving at their viewpoint,” Coleman said.

If neither side is willing to acknowledge its role in the coarsening of debate, it may be impossible to move forward.

“What leaders would have to do is not only change their tone but agree to have the same conversation at the same time,” Martin said.

Arnie Arnesen, a New Hampshire-based progressive radio host and Sanders supporter, cited a chronic unwillingness to listen to and understand the other side of an issue, and a tendency to vilify those who disagree with us.

“We’ve encouraged a toxic brew that encourages angry people to take violent action,” she said.

Stripping the debate down to a single factor like gun control is also unhelpful, when a combination of political, social, and mental factors likely brought Hodgkinson to that baseball field. Arnesen cautioned against focusing too much on the easy or obvious answers.

“You can’t kill all the angry people and you can’t kill all the resentment…. It’s not going to be the way out,” she said.

The causes of that anger and resentment are deeper, and politicians need to recognize and understand that to have any hope of fixing it.

“Put on your big boy pants and start addressing it like it is a complex problem,” Arnesen said.